Stromberg WW Carburetors for GMC Trucks

Until 1966 GMC light trucks used mostly GMC engines; after that they shared drive trains with Chevrolet. Medium and heavy duty GMC trucks used their own gasoline engines until 1974.

In the 1960s and 70s these were mostly V6 engines ranging in size from 305 CID to 478 CID; there was also a 503 CID straight 6, a 637 CID V8 and a 702 CID V12. All of the V6 and V12 engines used Stromberg WW or WWC carburetors; the V12 used two of them. We have complete listings of GMC carburetor kits and parts here.

The Stromberg WW-series came in two main variations, the WW and WWC. The WW is the smaller of the two, and is often mistaken for a Carter BBD carburetor. In fact, Stromberg WWs and Carter BBDs were used interchangeably on Mopar applications.

Stromberg WWC for GMC
Top view of a Stromberg WWC carburetor.
Stromberg WW for GMC
Front view of the smaller Stromberg WW carburetor

One quick way to tell a WW carburetor is that it has a large accelerator pump lever across the top of the carb. WWC carbs don’t have this lever.

There are many versions of these carbs that look similar, so it’s essential to check the carb number when ordering a kit. The carb number appears on these in a couple of different places. As shown in the pictures, it’s often on a round tag that looks like a washer on the top of the carb. This will usually have the vendor number shown in the table below. Sometimes there is a conventional tag with a GMC number. In many cases there is a ‘Code number’ stamped onto the top part of the carburetor – on the flat area on the float bowl cover.

All WW carburetors use our F77 float, listed here. Unfortunately, there aren’t any new floats for the larger WWC carburetor.

 

 

Stromberg WW/WWC Carburetors for 1960-66 GMC Applications

Year Engine Type GM Part No. Vendor No. Code No. Notes Carb Kit Float
1960 305C V6 WW-2 2391843
2391844
380977
380980
23-123A
23-124A
CK4491 F77
1960 351 V6 WW-2 2382770
2382773
2382774
380972
380973
380974
23-120A
23-121A
23-122A
CK4491 F77
1960 401 V6 WWC-3 2382772 380978 23-125 CK738
1960 702 V12 WW-2 2382773 380979 23-126B uses 2
7000
CK4491 F77
1962 305C V6
305D V6
WW 2427805 381031 23-133A except
L-4000
CK4491 F77
1962 305C V6 WW 2427807 381033 23-135A L-4000 CK4491 F77
1962 351 V6 WW 2433601 381038 23-137 except
L-5000
SP-5000
CK4491 F77
1962 351 V6 WW 2433602 381039 23-138 L-5000 CK4491 F77
1962 351 V6 WW 2433603 381040 23-139 SP-5000 CK4491 F77
1962 401 V6 WW 2433608 381045 23-144 F77
1963 305E V6 WW 2445281 381076 23-151 1000 to
3500
CK4491 F77
1963 305C V6 WW 2445281 381076 23-151 4000 except
L & LH-4000
CK4491 F77
1963 305C V6 WW 2445282 381077 23-152 L & LH-4000 CK4491 F77
1963 351 V6 WW 2433601 381038 23-137 5000 except
L & LH-5000
CK4491 F77
1963 351 V6 WW 2433602 381039 23-138 L & LH-5000 CK4491 F77
1963 351 V6 WW 2433603 381040 23-139 SP-5000 CK4491 F77
1963 351 V6 WW 2433606 381043 23-142 Hydraulic
Governor
CK4491 F77
1963 401 V6 WW 2440817 381064 23-147 CK738 F77
1963 478 V6 WW 2440818 381065 23-148 CK738 F77
1963 702 V12 WW 2433607 381044 23-143 uses 2
7000
CK4491 F77
1964
1965
305E V6 WW 2453827 381094 23-153A except
L-Series
CK529 F77
1964
1965
305C V6 WW 2453827 381094 23-153A except
L-Series
CK529 F77
1964
1965
305C V6 WW 2456769 381103 23-158 L3500
L4000
CK529 F77
1964
1965
351 V6 WW 2433601 381038 23-137A except
L & SP series
CK4491 F77
1964
1965
351 V6 WW 2433602 381039 23-138A L4000
L5000
CK4491 F77
1964
1965
351 V6 WW 2433603 381040 23-139 SP5000 CK4491 F77
1964
1965
351 V6 WW 2433606 381043 23-142 Hydraulic
Governor
CK4491 F77
1964 401 V6 WWC 2440817 381064 23-147 except W5000
SP5000
CK738
1964 401 V6 WWC 2433601 381038 23-137A W5000 CK4491
1964 401 V6 WWC 2441975 381066 23-149 SP5000 CK738
1964 478 V6 WWC 2441975 381066 23-149 SP5000 CK738
1964 478 V6 WWC 2440818 381065 23-148 6500 CK738
1964 702 V12 WW 2433607 381044 23-143 uses 2
7000
CK4491 F77
1965 305E V6
305C V6
WW 2472952 381123 23-160 except
L Series
CK50 F77
1965 305E V6
305C V6
WW 2472953 381124 23-161 L3500
L4000
CK50 F77
1965 351 V6 WW 2472954 381126 23-163 except
L & SP series
CK526 F77
1965 351 V6 WW 2472955 381127 23-164 L5000 CK526 F77
1965 351 V6 WW 2472956 381128 23-165 SP5000 CK526 F77
1965 351 V6 WW 2472958 381131 23-168 Hydraulic
Governor
CK526 F77
1965 401 V6 WWC 2472960 381134 23-171 All H Series CK738
1965 401 V6
478 V6
WWC 2472961 381135 23-172 SP5000 CK738
1966 305C V6 WW 2485214 381164 23-181 HM-5500 CK50 F77
1966 351C V6 WW 2485215 381165 23-182 HM-5500
HM/JM-7500
CK526 F77
1966 351C V6 WW 2472955 381127 23-164 TM-7500 CK526 F77
1966 351M V6 WW 2487147 381168 23-185 RM-7500 CK738 F77
1966 351M V6 WW 2483900 381167 23-184 HM/JM/TM-7500
HM/TM-8500
CK738 F77
1966 401M V6 WW 2483900 381167 23-184 HM/JM/TM-7500
HM/TM/JM/WM-8500
CK738 F77
1966 401M V6 WW 2487147 381168 23-188 RM-7500 CK738 F77
1966 478M V6 WW 2487147 381168 23-185 RM-7500 CK738 F77
1966 478M V6 WW 2483900 381167 23-184 HM/JM/TM/WM-8500 CK738 F77
1966 637 V8 WW 2492166 381177 ~ All-9500 F77

The above table was adapted from the excellent 60-66 GMC Truck Site at http://6066gmcguy.com

 

Correct Size AFB for a Stock Chevy 350

Edelbrock AFB Carburetor
Carter Competition AFB

 

The Question…

How would a stock 290 hp 350 handle a 650 CFM carb? Would it be to much fuel?

The Answer…

 

No, the usual size on a stock engine like that is the 625-650 carburetor. (Carter calls it 625, Edelbrock says 650 – same carb). In fact, CFM refers to the maximum Cubic Feet per Minute of air/fuel mixture that a carburetor will flow. In other words, when the engine is operating at high speed at Wide Open Throttle (WOT), how much will the carburetor allow the engine to breathe. So, it is not that too big a carb (too many CFM) will provide too much fuel, rather that it will provide too much air and fuel. Now, if a carburetor provides too much fuel for the amount of air, then it will run too rich, but that’s not caused directly by the carburetor being too big.

As for the common Carter Competition AFBs (made up to 1984 by Carter and sold up to about 1998 made by Weber) and the current Edelbrock AFB, the primary side is the same size in the Carter 625/Edelbrock 650 as in the 500 cfm version so there wouldn’t be any difference in part throttle driveability between the 500 and 625. Maximum air flow for a stock engine like a 290 HP Chevy 350 is less than 500 cfm; if the secondary on the carb was a plain venturi type, you would have to use a small carb. However, on the AFBs there is a velocity valve which limits the secondary air flow so that you can use a slightly larger carb. It allows the 625 carb to work on a range of engine sizes. That’s why Edelbrock sells the 625/650 cfm carb for 350s in general.

By the way, the velocity valve is the counter weighted flapper below the secondary venturi clusters in many AFB carbs. Some, mostly smaller AFBs, didn’t use a velocity valve. The AVS carburetor – both the Carter AVS from the 1960s to the early 1970s and the new Edlebrock Thunder AVS – use a valve above the venturis called an air valve, giving more carefully controlled airflow on the secondary side. This will be for another post.

At The Carburetor Doctor we’ve got a full range of rebuild kits for all Carter AFB carburetors here.

Edelbrock AFBs and Carter Competition AFBs from 400 to 750 cfm use our kit CK294 and F27:

CK294 Carter and Edelbrock AFB kit
Carburetor Rebuild Kit for Edelbrock and Carter Performance AFB Carburetors

 

Our CK294 kit features a complete ethanol-resistant Viton accelerator pump assembly (not just the cup!), needles/seats with the solid needle and optional spring-loaded needle for off-road use as well as quality gaskets, instructions and other parts as shown.

Holley 885FFC cfm

Holley 885FFC carburetor for 1949-51 Mercury

The question…

 

I have a 1951 Lincoln, with a 337 Ci Flathead, and am interested in rebuilding the original carb, a Holley 885 FFC

Before I do this, I am interested in knowing the CFM of said carb. It has been suggested that I have a 500-600 cfm for that size of engine, which is 100 % stock

Can you help me out with the CFM.

The answer…

As far as I know, there aren’t any good published cfm figures for this carburetor. Even if there were, it’s difficult to compare 2 bbl figures to the numbers for common 4 bbl carburetors, since the standard pressure drop for measuring cfm is different for 2 bbls and 4 bbls. So… you can compare 4 bbl numbers to each other, and 2 bbl numbers to each other, but cross comparison is harder.

Having said that, the 885 FFC is about the same size as later model 2300 350-500 cfm Holley 2bbls.

The Holley 885 FFC is the version of the 885 used on 1949-51 Mercury engines and Lincolns. There are other 885s, such as the 885 FFG that was used on trucks for a number of years. More details, along with carb kits and parts are on our site here.

If you’re rebuilding one of these carburetors, you’ll want our kit CK409:

CK409 carburetor rebuild kit for Holley 885FFC
CK409 Carburetor Rebuild Kit for Holley 885FFC Carburetors

This kit is made in the USA, ethanol-compatible and features hard-to-find parts such as the idle mixture screws and springs, float bumper spring and more. It also includes instructions and an exploded diagram. We also have a detailed factory service manual – CM409.

1949-51 Holley 885FFC specifications

I have also posted the specification sheets from the Holley carburetor manual for these carburetors on The Old Car Manual Project site.